BL20 Codesys Gateway Controls Image Processing Machine

The PALC unit image processing systems from ISW use Turck’s Codesys programmable BL20 gateway to check data matrix codes and plain text

The PALC unit (Package Aggregation Line Controller) is mostly used in the pharmaceutical sector. In its standard application, the machine marks a folded box with a unique serial number, product specific data and a data matrix code. It then checks the quality of the print. This is necessary to guarantee readability at the end customer (i.e., in the drugstore).

The PALC unit consists of a conveyor belt which feeds the folded boxes to a camera with a lighting system. A photoelectric sensor at the entry initiates a start trigger for the printing and measuring process. This is combined with another signal from a rotary encoder at the motor, which triggers the printer and camera at the right time. The camera checks the quality of the print on the basis of parameters taught. If the print result does match the target values, a compressed air nozzle blows this folded box from the conveyor belt to a reject chute. Another photoelectric sensor triggers the compressed air nozzle to blow the bad boxes (NOK) from the belt into the reject chute.

Easy Handling

Both photoelectric sensors are from Banner Engineering, Turck’s partner for optoelectronic solutions. The simplicity of the system is also its strength: “We didn’t have to teach the system or do anything similar. The photoelectric sensor is fitted with a reflector to act as a reflex sensor. Any foreground or background rejection is unnecessary here,” Tobias Wichmann says. The Turck compressed air sensor (M12E-VP44X-H1141), which is located at the maintenance unit of the compressed air nozzle and monitors the compressed air present as required, also offers easy handling.

Codesys Gateway as PLC

“The PLC is the core of the system,” says ISW representative Wichmann. In this case, it’s the programmable BL20 gateway from Turck that handles the control task. “All signals come together on the PLC and are processed: the signals of the IPC, the sensors, trigger signals, signals of the camera inspection and compressed air monitor and more,” Wichmann continues. “Turck’s Codesys programmable BL20 gateway has exactly the right dimensions for this task. Naturally, the PLCs of major manufacturers could also handle this task but would be unnecessarily expensive and complex. Another benefit was the fact that we already had experience with Codesys in the company and could program our solution quickly with the BL20. The choice of a suitable controller for the PALC was therefore easy to make.” The communication between the industrial PC and the gateway is implemented via a TCP/IP Ethernet connection.